I’ve spent some time roughing out the case and dial. I’ve been worried about the thickness of the calendar mechanism, however I think the whole thing actually looks pretty good nestled within a deep crystal. This elevates the mechanism, giving it dimensionality. It’s almost like a miniature orrery on top of the watch!
There’s a lot of stuff online about grinding sapphire. There’s also a lot about working with polycarbonate and acrylic, and applying (automotive) hard coats to resist scratches.
The case, dial, and hands will undergo countless iterations sometime later. For now I only need to be in the ballpark, so that I can finish designing the mechanism. There’s still a lot to do before I rapid prototype the whole thing at 4x scale.
At the moment, I’m working out the day and month adjustment mechanisms (shown above in red). A user has to be able to press these pins with a paper clip to set the date. The mechanisms need to advance the ratchet wheels by one click, and then spring back into place.
Making A Perpetual Calendar Watch 